Wire bonded electronic devices to round wire

ABSTRACT

A disclosed circuit arrangement includes a flexible substrate. A layer of pressure sensitive adhesive (PSA) is directly adhered to a first major surface of the substrate. One or more metal foil pads and electrically conductive wire are attached directly on a surface of the PSA layer. The wire has a round cross-section and one or more portions directly connected to the one or more metal foil pads with one or more weld joints, respectively. An electronic device is attached directly on the surface of the layer of PSA and is electrically connected to the one or more portions of the round wire by one or more bond wires, respectively.

FIELD OF THE INVENTION

The disclosure describes wire bonding electronic devices to round wiringon a substrate.

BACKGROUND

There are a number of applications in which electronics are attached tovarious articles to provide a function that is ancillary to the functionof the article or work in conjunction with the article to provide adesired function. Such applications may involve radio frequency (RF)transponders or light-emitting diodes (LEDs), for example.

A number of design objectives present challenges for making suitablestructures to carrying the aforementioned electronic devices, and insome instances, compromises may be required. Examples of designobjectives include low cost, low profile, flexibility, and durability.

Mounting electronic devices on flexible substrates is a common approachfor making structures that are flexible and durable. However, approachesthat involve print-and-etch processes may be more costly than desired.The expense is attributable in part to the print-and-etch processes usedin creating the wiring pattern. Expensive chemicals are required forprint-and-etch processes, and hazardous waste is a byproduct. Also, leadframes are often used as carriers for the electronic devices, creating astructure having a higher profile than may be desired.

SUMMARY

The above summary is not intended to describe each disclosed embodiment.The figures and detailed description that follow provide additionalexample embodiments.

In one embodiment, a circuit arrangement includes a flexible substratehaving first and second major surfaces. The first major surface isopposite the second major surface. A first layer of pressure sensitiveadhesive (PSA) has third and fourth major surfaces. The third majorsurface is opposite the fourth major surface, and the fourth majorsurface is directly adhered to the first major surface of the substrate.One or more metal foil pads are attached directly on the third majorsurface of the PSA layer. Electrically conductive wire is attacheddirectly on the third major surface of the first layer of PSA. The wirehas a round cross-section and one or more portions directly connected tothe one or more metal foil pads with one or more weld joints,respectively. An electronic device is attached directly on the thirdmajor surface of the first layer of PSA and is electrically connected tothe one or more portions of the round wire by one or more bond wires,respectively.

In another embodiment, a method of making a circuit arrangement includesattaching first and second metal foil pads to a flexible substrate by afirst layer of pressure-sensitive adhesive (PSA) on the flexiblesubstrate. An electronic device is attached to the substrate by thepressure-sensitive adhesive proximate the first and second metal foilpads. One or more wire segments of wire are attached to the substrate bythe first layer of PSA. The one or more wire segments have a round crosssection and first and second portions over the first and second metalfoil pads, respectively. The first and second portions of the one ormore wire segments are welded to the first and second metal foil pads,respectively. The electronic device is wire bonded to the first andsecond portions of the one or more wire segments, making first andsecond wire bond joints between first and second bond wires and thefirst and second portions of the one or more wire segments,respectively.

In another method of making a circuit arrangement, first and secondmetal foil pads are picked and placed on a flexible substrate. The firstand second metal foil pads are attached to the substrate by a firstlayer of pressure-sensitive adhesive (PSA) on the flexible substrate. Anelectronic device is attached to the flexible substrate by thepressure-sensitive adhesive proximate the first and second metal foilpads. One or more wire segments of wire are attached to the substrate bythe first layer of PSA. The one or more wire segments have round crosssections and first and second portions over the first and second metalfoil pads, respectively. The first and second portions of the one ormore wire segments are welded to the first and second metal foil pads,respectively. The electronic device is wire bonded to the first andsecond metal foil pads, making first and second wire bond joints betweenfirst and second bond wires and the first and second metal foil pads,respectively.

BRIEF DESCRIPTION OF THE DRAWINGS

Other aspects and advantages will become apparent upon review of theDetailed Description and upon reference to the drawings in which:

FIG. 1 shows an example of an RF transponder arrangement;

FIG. 2 shows a cross section of a portion of the RF transponderarrangement of FIG. 1 taken in direction 2;

FIG. 3 shows the structure of FIG. 2, with an added release liner;

FIG. 4 shows an alternative to the structure of FIG. 2;

FIG. 5 shows a release liner disposed directly on the second PSA layer;

FIG. 6 shows a plan view of an electronic device wire bonded to aportion of round wire that is connected to a metal foil pad;

FIG. 7 shows a cross section of a portion of the structure of FIG. 6taken in direction 7;

FIG. 8 shows a plan view of an alternative connection between anelectronic device and round wire;

FIG. 9 shows a cross section of a portion of the structure of FIG. 8taken in direction 9;

FIG. 10 shows an alternative antenna pattern and the connection of theantenna wires to the bond wires;

FIG. 11 shows an LED-based lighting arrangement having wire bonds fromthe LEDs to power wires welded to metal foil pads;

FIG. 12 shows a circuit arrangement in which multiple electronic devicesmay be wire bonded to multiple metal foil pads, in combination with apair of the electronic devices being wire bonded to one another; and

FIG. 13 is a flowchart of a process of making a circuit arrangementhaving an electronic device using wire bonding approaches to connect theelectronic devices to round wire segments.

DETAILED DESCRIPTION

In the following description, numerous specific details are set forth todescribe specific examples presented herein. It should be apparent,however, to one skilled in the art, that one or more other examplesand/or variations of these examples may be practiced without all thespecific details given below. In other instances, well known featureshave not been described in detail so as not to obscure the descriptionof the examples herein. For ease of illustration, the same referencenumerals may be used in different diagrams to refer to the same elementsor additional instances of the same element. Terms such as over, under,top, bottom, above, below, may be used herein to refer to relativepositions of elements as shown in the figures. It should be understoodthat the terminology is used for notational convenience only and that inactual use the disclosed structures may be oriented different from theorientation shown in the figures. Thus, the terms should not beconstrued in a limiting manner.

In the disclosed structures, RF transponder arrangements, LED-basedlighting apparatuses, and other circuit arrangements of electronicdevices are constructed using round wire rather than printed-and-etchedpatterns of conductive material for wiring the electronic devices.“Wire” as used herein does not refer to printed or printed-and-etchedpatterns of conductive material. Rather, as used herein, wire refers toone or more strands of conductive material that have been made, forexample, by drawing the conductive material through draw plates. Using afine gauge copper wire to make antennas or provide power to LEDseliminates the use of environmentally hazardous chemicals as would berequired for printing and etching. Though challenges are presented inconnecting the wire to electronic devices such as RF transponders, LEDs,or discrete components, the disclosed approaches simplify making theconnections. Electronic devices as used herein refers to integratedcircuit (IC) components as well as to discrete components such ascapacitors, resistors, etc.

The disclosed approaches provide low-cost, low-profile, flexible, anddurable structures. The approaches simplify attachment of wiring toelectronic devices such as RF transponders, LEDs, and discretecomponents, such as capacitors and resistors. An example of thedisclosed circuit arrangements includes a flexible substrate and a layerof pressure sensitive adhesive (PSA) adhered to one of the surfaces ofthe flexible substrate. The flexible substrate may be any material thatsatisfies application requirements. Examples include polyimide,polyester, polyethylene terephthalate (PET), a polyelectrolytemultilayers (PEMs), paper, high-density polyethylene, and vinyl. Exampletypes of pressure sensitive adhesives include acrylic, natural rubber,or synthetic rubber. The combination of features in the disclosedstructures provides a substantial improvement in durability overprevious structures. The disclosed structures have been tested towithstand hundreds of thousands of flexes, far surpassing prior artstructures. The improved durability allows the structures to be deployedin new applications, such as those that include wearable devices.

Metal foil pads and one or more electronic devices are attached to theexposed surface of the PSA layer. The metal pads may be copper oraluminum, depending on application requirements. Electrically conductivewire is also attached to the exposed surface of the PSA layer. The wirehas a round cross-section and portions of the wire are directlyconnected to the metal foil pads with weld joints.

The electronic device(s) are connected to the wire, either directly orindirectly, by bond wires. In a direct connection, one end of the bondwire is connected to the electronic device and the other end of the bondwire is connected to the portion of the wire that is connected to themetal foil pad. In an indirect connection, one end of the bond wire isconnected to the electronic device, and the other end of the bond wireis connected to the metal foil pad.

Each metal foil pad serves as a connection site between the round wireand the electronic device, providing a stable surface to which the roundwire and bond wires can be connected. Prior approaches have used leadframes to connect electronic devices to conductors. However, the leadframes introduce additional bulk to the structure, which may beundesirable for some applications. The metal foil pads eliminate theneed for lead frames, thereby reducing the profile of the structure.

The structure having round wire attached to a flexible substrate by aPSA layer provides a substantial reduction in cost over structureshaving printed-and-etched wiring patterns. The structure is amenable towelding and wedge bonding, which eliminates environmental concernsassociated with lead-based solders and costs and durability associatedwith lead-free solders. As described below, various aspects of thestructure make the structure both flexible and durable.

FIG. 1 shows an example of an RF transponder arrangement 100. The RFtransponder arrangement includes a substrate 102, an RF transponder 104,and coil antenna wire 114. The particular functions of the RFtransponder are application dependent. Example applications include RFIDand near-field communications. In general, the transponder modulates anddemodulates an RF signal and processes information according to theapplication. The RF transponder may be packaged or unpackaged (a “baredie”) according to application requirements. The substrate may be eitherrigid or flexible, also depending on application requirements. In oneimplementation, the substrate is a flexible substrate and is one of apolyethylene terephthalate (PET), a polyelectrolyte multilayers (PEMs),paper, a high-density polyethylene, or a vinyl, for example.

Rather than using expensive print-and-etch techniques to make antennawiring for the RF transponder, wire may be glued to the substrate. Thewire may be bare wire or wire encased in a dielectric jacket. The wiremay be made of any material suitable for the application. The antennawire 114 may be a fine gauge, round (round cross-section), bare wire.For example, 44 gauge (AWG) copper or silver-coated copper wire has beenfound to be suitable for some applications. However, different gaugesmay be suitable for different applications. For an implementation havingbare antenna wire, an insulating bridge (not shown) may be disposedbetween intersecting portions 115 of the antenna wire.

The wire is glued to the surface of the substrate with a polymeradhesive 116. The adhesive may be pressure sensitive, which keeps thewire in place as the antenna pattern is formed on the substrate. It willbe appreciated that other types of adhesives may be suitable fordifferent applications. The RF transponder 104 may be attached to thesubstrate 102 using the same adhesive as is used for the antenna wire.In an example implementation, the wire and transponder may be applied toan adhesive layer as carried on adhesive transfer tape.

Metal foil pads 110 and 112 are attached to the substrate 102 by theadhesive 116 and located proximate the RF transponder 104. The distanceseparating each of pads 110 and 112 and the RF transponder is suitablefor wire bonding of the RF transponder to the end portions of theantenna wire. The pads may be copper or aluminum and of a thicknesssuitable for wedge bonding and welding. In one implementation, the metalfoil pads are 1 mm² and formed from 10 mil copper foil.

Antenna wire 114, which is a single coiled wire segment in the example,has portions for connecting to bond wires 122 and 124. In the coilantenna pattern, connections to the RF transponder are made at endportions 106 and 108 of the antenna wire. For other antenna patterns,the connection to the RF transponder may be at portions between the endportions of the antenna wire (e.g., FIG. 10). End portions 106 and 108of the antenna wire are connected to pads 110 and 112 by weld joints. Inone implementation, the end portions 106 and 108 are compressed againstthe pads 110 and 112 prior to welding, enhancing strength of thesubsequently formed weld joint and forming a flat area of contact forwire bonding the antenna to the RF transponder.

FIG. 2 shows a cross section of a portion of the RF transponderarrangement 100 of FIG. 1 taken in direction 2. The flexible substrate102 has a first major surface 202 and a second major surface 204opposite the first major surface. One major surface of the PSA layer 116is directly adhered to the first major surface 202 of the substrate.

RF transponder 104, metal foil pads 110 and 112 and the wire (FIG. 1,#114) are directly adhered to the major surface 206 of the PSA layer116. It will be recognized that the portions of the wire 114 that aredirectly adhered to the PSA layer are not shown in FIG. 2 as the crosssection shows only end portions 106 and 108 of the wire 114. The endportions 106 and 108 of the wire are connected to the metal foil pads110 and 112, respectively, with weld joints. The weld joints may beformed by friction or ultrasonic welding, for example.

The RF transponder 104 is electrically connected to the portions 106 and108 of the wire by bond wires 122 and 124, respectively. In thestructure of FIG. 2, the bond wires are directly connected to the wireportions 106 and 108. Bond wire 122 connects bond pad 212 to wireportion 106, and bond wire 124 connects bond pad 214 to wire portion108. Wedge bonding or ball bonding may be used to connect the bondwires, depending on application requirements and restrictions.

The metal foil pads 110 and 112 provide stable and visible structuresthat are dedicated to connecting the bond wires 122 and 124 to the wireportions 106 and 108. The metal foil pad 110 is only directly connectedto wire portion 106, and metal foil pad 112 is only directly connectedto wire portion 108.

A polymer conformal coating 216, which is sometimes referred to as a“glob-top,” covers the RF transponder 104, bond wires 122 and 124, metalfoil pads 110 and 112, and wire portions 106 and 108. The polymerconformal coating may be an epoxy, acrylic, polyurethane, or silicone,depending on application requirements. The transponder arrangement 100of FIG. 1 does not show the polymer conformal coating in order to avoidobscuring elements of the arrangement.

FIG. 3 shows the structure of FIG. 2, with an added release liner 220.The release liner is disposed directly on the surface 206 of the PSAlayer 116 and is separable from the PSA layer, which allows the RFtransponder arrangement 100 (FIG. 1) to be attached to a desired object.

FIG. 4 shows an alternative to the structure of FIG. 2. Instead of aconformal coating 216 that covers the RF transponder 104 and bond wires,an underfill 230 fills the gaps between the bond wires and the PSA layer116, covers the RF transponder 104 and metal foil pads 110 and 112 andpartially covers the bond wires. The underfill may be a soft, flexibleacrylic and provides a lower profile than the conformal coating 216.

In addition to the underfill, a second PSA layer 232 is disposeddirectly on the first PSA layer 116 and over the underfill and metalfoil pads, bond wires, and RF transponder.

FIG. 5 shows a release liner 220 disposed directly on the second PSAlayer.

In an alternative to the implementations of FIGS. 4 and 5, the underfill230 may be omitted, and the second PSA layer retained. The resultingstructures would be similar to the structures of FIGS. 4 and 5, but haveno underfill. The second PSA layer in each alternative structure wouldconform more closely to metal foil pads 110 and 112, the bond wires 122and 124, and the RF transponder 104.

FIG. 6 shows a plan view of an electronic device 302 wire bonded to aportion of round wire 304 that is connected to a metal foil pad 306. Theelectronic device 302, wire 304, and metal foil pad 306 arerepresentative of the RF transponder 104, wire 114, and metal foil pad110 of FIG. 1, for example. In alternative applications, the portion ofthe electronic device may be an LED or discrete electronic component andthe wire 304 may correspond to power or control wires.

A portion 308 of the wire 304 that is disposed on the metal foil pad 306is compressed, forming a flat contact area 310 that is amenable to wirebonding. In addition to forming a contact area for wire bonding,compression of the intersection mechanically interlocks a portion of thewire 304 with the metal foil pad, thereby providing a stable target forwelding the wire at the flat contact area 310 to the metal foil pad.

Once the wire 304 has been welded to the metal foil pad 306 at the flatcontact area 310, the electronic device may be wire bonded to the flatcontact area 310. One end 312 of the bond wire 314 is bonded to flatcontact area 310, and the other end 316 of the bond wire is bonded tothe contact pad 318 on the electronic device 302. The bond wire may bewedge bonded to provide a low profile. In other applications, the bondwires may be ball bonded. The weld joint of the flat contact area 310 tothe metal foil pad 306 and the wire bond to the flat contact area 310may be replicated for other portions of the wire 304 or for otherportions of other wire segments.

FIG. 7 shows a cross section of a portion of the structure of FIG. 6taken in direction 7. The compressed portion 308 of the wire 304 doesnot have a round cross section as do other portions of the wire. Rather,the compressed portion has a first flat contact area 310 wire bonded tobond wire 314, and a second flat contact area 330 that is welded to themetal foil pad 306. Compression of wire portion 308 creates a recessedportion 332 in the metal foil pad 306. The compressed portion 308 withinthe recessed portion 332 provides a stable target for welding the wireto the metal foil pad, which might otherwise be problematic.

FIG. 8 shows a plan view of an alternative connection between anelectronic device 348 and round wire. In the arrangement of FIG. 8, thebond wires are directly connected to the metal foil pads rather than tothe round wire. Portions 350 and 352 of round wire are welded to metalfoil pads 354 and 356, respectively. Bond wires 358 and 360 are wirebonded directly to the metal foil pads 354 and 356, respectively. Eachmetal foil pad is directly electrically connected to only a wire portionand to the bond wire. The indirect attachment of the bond wires to thewire portions 350 and 352 may be used in place of the direct attachmentapproaches shown in FIGS. 1-7 and FIGS. 10 and 11.

FIG. 9 shows a cross section of a portion of the structure of FIG. 8taken in direction 9. Though a conformal coating 370 is shown similar tothe conformal coating 216 of FIG. 2, an alternative implementation mayhave an underfill 230 and additional PSA layers 232 as in the structuresof FIGS. 4 and 5. Alternatively, the underfill 230 may be omitted, andthe second PSA layer retained. The resulting structure would be similarto either of the structures of FIGS. 4 and 5, but have no underfill. Thesecond PSA layer in each alternative structure would conform closely tothe electronic device 348, round wire portions 350 and 352, wire metalfoil pads 354 and 356, the bond wires 358 and 360, and the RFtransponder 104.

FIG. 10 shows an alternative antenna pattern and the connection of theantenna wires to the bond wires. The antenna pattern includes wiresegments 402 and 403 and having the wire bonds at portions of theantenna wire that are between end portions of the antenna wire. It willbe appreciated that in addition to the antenna patterns of FIGS. 1 and10, the disclosed structures are adaptable for any of the many differentantenna patterns known in the art to be suitable for RF transponderapplications. As with the RF transponder arrangement 100 of FIG. 1, RFtransponder arrangement 400 includes a substrate 404 and an RFtransponder 406. The antenna and RF transponder may be adhered to thesubstrate as described for the RF transponder arrangement 100.

Metal foil pads 412 and 414 are attached to the substrate 404 by PSAlayer 116 and located proximate the RF transponder 406. Portions 422 and424, which are between the end portions 426 and 428 of wire segments 402and 403, are laid over the metal foil pads 412 and 414, respectively.The wire portions 422 and 424 are compressed as described above. Thebond wires 408 and 410 connect the RF transponder 406 to flat contactareas (e.g., FIGS. 6, 7) at portions 422 and 424 of the wire segments402 and 403.

FIG. 11 shows an LED-based lighting arrangement 500 having wire bondsfrom the LEDs to power wires welded to metal foil pads. The lightingarrangement includes a substrate 502, such as that described above,along with LEDs 504, 506, and 508 and power wires 510 and 512 that areattached to the substrate. The LEDs may be bare dice or packaged dice.Additional control wires (not shown) may be attached to the substrateand connected to the LEDs in a manner similar to the manner in which thepower wires are connected to the LEDs. The type of wire used for thepower wires 510 and 512 may be the same as the type of wire used for theantenna wire 114 of FIG. 1. Also, the power wires and LEDs may beattached to the substrate using an adhesive layer as described above forthe RF transponder arrangement.

LEDs 504, 506, and 508 are connected to the power wires 510 and 512 byrespective pairs of bond wires wire bonded to metal foil pads. Forexample, bond wires 514 and 516 connect LED 504 to the power wires 510and 512, respectively, on metal foil pads 518 and 520. The connectionsare similar to the connections described above for the RF transponderarrangement 100 and connections illustrated in FIGS. 2-9. Though notshown, it will be recognized that current regulating circuits, such asresistors, may be connected between the power wiring and the LEDs.

FIG. 12 shows a circuit arrangement 600 in which multiple electronicdevices 602, 604, and 606 may be wire bonded to multiple metal foil pads608, 610, 612, 614, 616, and 618, in combination with a pair 604 and 606of the electronic devices being wire bonded one to another. The wirebond connections may be as shown and described above.

FIG. 13 is a flowchart of a process of making a circuit arrangementhaving an electronic device using wire bonding approaches to connect theelectronic devices to round wire segments. Metal foil pads are pickedand adhered to the PSA layer at desired locations at block 702. One ormore electronic devices are picked and adhered to the PSA layer atdesired locations at block 704. The locations of the metal foil pads andelectronic device(s) are according to application requirements. Thesubstrate, PSA layer, metal foil pads, electronic device(s), and bondwire are as described above. The metal foil pads and electronic devicesmay be picked and placed on the PSA layer using known robotic equipment.

At block 706, one or more round wire segments are attached to thesubstrate with the PSA. Selected portions of the round wire segment(s)pass over the metal foil pads. The wire segment(s) may implement adesired antenna pattern for an RF transponder or power and control wiresfor LEDs. The type of wire may be as described above.

At block 708, the portions of the wire segment(s) and the cross wiresmay be optionally compressed to form flat contact areas for wire bondingand create a stable target for welding the wire portions to the metalfoil pads. In an example approach, the round wire portions may becompressed by robotic action. A robot may have an image sensor andprocessor for identifying portions of the wire that overlay the pads.Based on the imagery, a head unit may be positioned above a portion ofthe wire to be compressed. The head unit may include a pneumaticallyactuated piston having a cross section that is approximately the size ofthe diameter of the round wire. Once in position and at the desiredheight, the piston is driven by pneumatic force in a hammer action atthe joint. The striking of the piston against the round wire portionforms a flat contact area for wire bonding and presses the flattenedportion of the wire into a recess thereby formed in the metal foil pad.

At block 710, the compressed portions are welded to the metal foil pads.In one approach, the joints may be welded using an ultrasonic welderthat is guided by digital imagery and robotic control.

The wire bonding head of a wire bonder is guided to the metal foil padsat block 712. The wire bonder may be imagery-based, using images of themetal foil pads and wire portions to position the wire bonding head. Atblock 714, the electronic device is electrically connected to roundwire, either directly by a wire bond connection on the flat contactareas of the wire portions, or indirectly by a wire bond connection onthe metal foil pad. The bond wires may be wedge bonded or ball bonded,depending on application requirements. In implementations in whichinsulated wire is used, the welding and wedge bonding at theintersections of the cross wires and wire segments effectively removesthe dielectric material at the joints. Though blocks 702-714 arepresented in a particular order, it will be recognized that the order ofprocessing may vary according to implementation requirements.

At block 716, a conformal coating or an underfill is applied to the wirebonded circuit arrangement. The conformal coating may be as describedabove with reference to FIG. 2 and covers the metal foil pads, bondwires, and electronic device. A lower profile and flexible structure maybe made by applying an acrylic underfill to the structure. The underfillis flexible, fills the gap between the bond wires and the PSA layer andcovers the wire bond joints. If an underfill is used in the structure, asecond PSA layer may be disposed over the first PSA layer and coveringthe electronic device, bond wires, round wire, and metal foil pads. Arelease liner is attached to the PSA layer at block 718.

Although the figures illustrate circuit arrangements that include RFtransponders and LEDs, it will be recognized that the disclosedapproaches for wire bonding to round wire are similarly applicable toother electronic devices, such as other integrated circuit (IC)components or discrete components such as capacitors, resistors, etc.

The present invention is thought to be applicable to a variety ofapplications. Other aspects and embodiments will be apparent to thoseskilled in the art from consideration of the specification and practiceof the circuits and methods disclosed herein. It is intended that thespecification and illustrated embodiments be considered as examplesonly, with a true scope of the invention being indicated by thefollowing claims.

What is claimed is:
 1. A method of making a circuit arrangement,comprising: attaching first and second metal foil pads to a flexiblesubstrate by a first layer of pressure-sensitive adhesive (PSA) on theflexible substrate; attaching an electronic device to the flexiblesubstrate by the first layer of PSA proximate the first and second metalfoil pads; attaching one or more wire segments of electricallyconductive wire to the flexible substrate by the first layer of PSA, theone or more wire segments having a round cross section and first andsecond portions disposed over the first and second metal foil pads,respectively; welding the first and second portions of the one or morewire segments to the first and second metal foil pads, respectively; andwire bonding the electronic device to the first and second portions ofthe one or more wire segments making first and second wire bond jointsbetween first and second bond wires and the first and second portions ofthe one or more wire segments, respectively.
 2. The method of claim 1,further comprising: compressing each of the first and second portions ofthe one or more wire segments into flat contact areas with the first andsecond metal foil pads, respectively; and wherein the wire bondingincludes making the first and second wire bond joints between the firstand second bond wires and compressed parts of the first and secondportions of the one or more wire segments.
 3. The method of claim 1,wherein the first and second metal foil pads are directly electricallyconnected to only the first and second portions, respectively, of theone or more wire segments.
 4. The method of claim 1, wherein theelectronic device is one of an RF transponder, an LED, or a discretecomponent.
 5. The method of claim 1, further comprising forming apolymer conformal coating that covers the first and second metal foilpads and the electronic device.
 6. The method of claim 5, furthercomprising attaching a release liner directly on the first layer of PSAand over the polymer conformal coating.
 7. The method of claim 1,further comprising: underfilling gaps between the first and second bondwires and the first layer of PSA; attaching a second layer of PSAdirectly on the first layer of PSA and over the first and second metalfoil pads, first and second bond wires, and the electronic device; andattaching a release liner directly on the second layer of PSA.
 8. Themethod of claim 1, wherein the flexible substrate is one of a polyimide,polyester, polyethylene terephthalate (PET), a polyelectrolytemultilayers (PEMs), paper, a high-density polyethylene, or a vinyl.
 9. Amethod of making a circuit arrangement, comprising: picking and placingfirst and second metal foil pads on a flexible substrate; attaching thefirst and second metal foil pads to the flexible substrate by a firstlayer of pressure-sensitive adhesive (PSA) on the flexible substrate;attaching an electronic device to the flexible substrate by the firstlayer of PSA proximate the first and second metal foil pads; attachingone or more wire segments of electrically conductive wire to theflexible substrate by the first layer of PSA, the one or more wiresegments having a round cross section and first and second portionsdisposed over the first and second metal foil pads, respectively;welding the first and second portions of the one or more wire segmentsto the first and second metal foil pads, respectively; and wire bondingthe electronic device to the first and second metal foil pads makingfirst and second wire bond joints between first and second bond wiresand the first and second metal foil pads, respectively.
 10. The methodof claim 9, further comprising compressing each of the first and secondportions of the one or more wire segments into flat contact areas withthe first and second metal foil pads, respectively, before the welding.11. The method of claim 9, wherein the first and second metal foil padsare directly electrically connected to only the first and second bondwires, respectively, and to the first and second portions, respectively,of the one or more wire segments.
 12. The method of claim 9, wherein theelectronic device is one of an RF transponder, an LED, or a discretecomponent.
 13. The method of claim 9, further comprising forming apolymer conformal coating that covers the first and second metal foilpads and the electronic device.
 14. The method of claim 9, furthercomprising attaching a release liner directly on the first layer of PSAand over the polymer conformal coating.
 15. The method of claim 9,further comprising: underfilling gaps between the first and second bondwires and the first layer of PSA; attaching a second layer of PSAdirectly on the first layer of PSA and over the first and second metalfoil pads, first and second bond wires, and the electronic device; andattaching a release liner directly on the second layer of PSA.
 16. Themethod of claim 9, wherein the flexible substrate is one of a polyimide,polyester, polyethylene terephthalate (PET), a polyelectrolytemultilayers (PEMs), paper, a high-density polyethylene, or a vinyl.